Let the data speak – what we need to know about COVID vaccines

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Last week, the FDA officially approved the Pfizer-BioNTech vaccine, now under the Comirnaty brand, for the prevention of COVID-19 infection in people over 16 years of age. For young people aged 12 to 15, it remains under emergency use authorization (EUA). Two other vaccines, one produced by Moderna and the other by Jassen, a subsidiary of Johnson & Johnson, are currently available for adults only through the EUA.

More than 171 million Americans have been fully immunized to date. However, many are reluctant to receive the vaccines due to skepticism about their efficacy, risk-benefit profile, and need. Meanwhile, the delta variant, a mutant virus more than twice as contagious as the original SARS-CoV-2, is spreading across the country, causing a resurgence of new COVID cases and hospitalizations.

Part of the confusion over vaccines has to do with how the pandemic continues to evolve. Scientists are conducting studies and analyzing data as fast as the virus mutates, constantly renewing our understanding of the disease. But the quality of the data is mixed. It doesn’t help that the media is prematurely discussing the unpublished, unpaired results. Organizations that relay information to the public (eg, White House, CDC, medical societies, local clinics) lack coordination, often giving conflicting opinions.

The FDA approval finally grants a higher degree of legitimacy, in the hope that its designation will dispel doubts and increase vaccination.

Let’s briefly review the existing data on COVID vaccines.

Are vaccines effective?

The short answer is yes. All three US vaccines have been subjected to large-scale and large-scale randomized controlled trials. In the Phase 3 trial that led to FDA approval, half of 43,847 adults received the Pfizer-BioNTech vaccine and the other half received a placebo. Subjects were followed for 3 to 6 months thereafter. The vaccine group had 77 confirmed cases of COVID-19 with one seriously ill person, compared to 833 in the placebo group with 21 seriously ill. This means that the vaccine is 91% effective in preventing infections and 95% effective in preventing serious illness.

Likewise, the Moderna vaccine was shown to be 94% effective in preventing symptomatic COVID-19 in a trial that followed 30,420 people for two months. Since these are two-dose vaccinations, the effectiveness is significantly reduced if only one dose is received. The Johnson & Johnson single-dose vaccine was 66% effective in preventing symptomatic COVID-19 and 85% effective in preventing serious illness in a trial that followed 43,783 people for two months. For reference, the effectiveness of the measles vaccine is 93% and that of the annual flu vaccine generally ranges between 40 and 60%.

Are vaccines effective against the delta variant?

Initial vaccine trials were performed when the original viral strain was dominant. When the delta variant began to circulate, researchers identified people who had fallen ill and examined their vaccination status. The Pfizer-BioNTech vaccine is 88% effective against the delta variant. A few other unpublished studies (whose scientific rigor or accuracy has yet to be reviewed) suggest that all three vaccines remained at least 70-80% effective against the delta variant.

Are vaccines safe?

While the majority of people report some sort of side effect from the vaccine, serious reactions are rare. The most common complaints are pain and swelling at the injection site, fatigue, headache, muscle pain, fever, and nausea. Serious events, such as anaphylaxis and heart attack, occur in 2-5% of people and the rate is similar between the vaccine and placebo groups.

How long does vaccine protection last?

Some people get COVID-19 despite being vaccinated. Vaccines work by stimulating our own immune system. Breakthrough infections are rare (less than 1%) in people with a competent immune system. Preliminary reports suggest that the strength of the immunization response may wane over time. Once this data is updated and evaluated, there will likely be a verdict on the “recall” shots.

Currently, there are approximately 1,000 ongoing clinical studies involving COVID-19 vaccines. Our interconnected society enables the real-time dissemination of what scientists observe and discover. However, being bombarded with ever-changing data can evoke a deep sense of uncertainty, anxiety and fatigue. One way to anchor ourselves is to objectively assess new information to better understand what’s going on.

Qing Yang and Kevin Parker are a married couple living in Springfield. Dr. Yang received her medical degree from Yale University School of Medicine and completed her residency at Massachusetts General Hospital. She is an anesthesiologist at HSHS Medical Group. Parker has helped formulate and administer public policy in various city and state governments across the country. He was previously the Group Information Director for Education at the Illinois Department of Innovation and Technology. This column is not intended to be a substitute for professional medical advice, diagnosis or treatment. Opinions are those of the authors and do not represent the views of their employers.


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